Not a answer to your question per se, but I ran into a very similar problem when I moved to a new apartment 2 years ago. Rather than upgrade everything to 802.11n (and suffer the whole issue of too many wireless cooks in the pot as everyone now has their own access point) I got two Homeplug v2 adapters and moved my router to my office. Cable modem connects to my coax, which is then plugged into a Homeplug. The 2nd Homeplug then goes to the WAN interface on my house router. Works like a charm and I can still use wired connections for all my workstations.
Just a thought. I would have considered the 802.11n route but there's way too much activity in my area to make that feasible for 8+ machines (my 802.11g access point does work well for the 2-3 wireless devices I use regularly though, especially now that my access point is in my office and spaced further away from my neighbors' APs).